Feinberg-Horodecki states of a time-dependent mass distribution harmonic oscillator M. Eshghi, R. Sever and S. M. Ikhdair Eur. Phys. J. Plus, 131 7 (2016) 223 Published online: 04 July 2016 DOI: 10.1140/epjp/i2016-16223-3